A power circuit breaker, which can be moved into a withdrawable-part or insertion rack, is shown, for example, in DE 35 44 227 A1. In a similar manner, high-voltage power circuit breakers in the medium-voltage range can also be moved by them being placed on a carriage, which can be moved by way of a crankshaft drive, cf. for example DE 100 06 427 C2.
Power circuit breakers, which can be inserted in a withdrawable-part rack, need to be able to be fixed in the withdrawable-part rack, in particular in the case of very high short-circuit currents. This is done in order to be able to ensure functional reliability during operation of the power circuit breaker.
As a result of the arrangement of the current path in the power circuit breaker, forces result which would produce a torque about the insertion shaft and would thus push the power circuit breaker out of the withdrawable-part rack if insufficient fixing were provided. As a result, the region of overlap between the insertion blades of the power circuit breaker in the isolating contact systems of the withdrawable-part rack would be reduced or eliminated. The formation of an arc associated with this may result in failure or destruction of the device.
In order to be able to fix the power circuit breaker securely in the withdrawable-part rack, it is known to latch the power circuit breaker in the withdrawable-part rack by way of a latching apparatus. In this case, holding systems are known which lock the power circuit breaker using relatively short lever arms. If a strong force is introduced, the power circuit breaker accordingly tends towards tipping movements, with the result that the mentioned disadvantages occur.
DE 92 12 149 U1 also discloses a device for fixing a power circuit breaker provided with a partition plate and in which a blocking lever, which is fixed on the withdrawable-part rack, can be brought by hand into a latched or an unlatched position, and the power circuit breaker is fixed in the latched position by way of a locking hook. The locking hook prevents a possible tipping movement of the power circuit breaker.
Analogous locking for a withdrawable-part rack equipped with a device for inserting the power circuit breaker does not, however, have to be undertaken by hand, which would then have the hidden risk of locking being forgotten.